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PubMed2026

Genomic population structure, antimicrobial susceptibility, and clinical features of Mycobacterium xenopi isolates, Frankfurt, Germany, 1995-2020.

Mycobacterium xenopi causes non-tuberculous mycobacterial pulmonary disease (NTM-PD) that is difficult to treat. However, data on the genomic population structure, antimicrobial susceptibility, and the clinical significance of this pathogen remain scarce. We analyzed 76 clinical M. xenopi isolates from 70 patients collected between 1995 and 2020 in Frankfurt am Main, Germany. All isolates underwent phenotypic drug susceptibility testing and whole-genome sequencing. Cluster analysis, including isolates from this study and all hitherto available high-quality M. xenopi genome data sets in the Sequence Read Archive (n = 11), was performed by core genome multilocus sequence typing. In our cohort, only 26.5% of patients met criteria for clinically relevant NTM-PD. Phylogenetic analysis identified three large hospital-associated clusters (≤10 allelic difference), each involving between 7 and 20 patients and persisting for over 18 years, suggesting prolonged transmission chains or a common environmental source. We also defined three major clades (≤50 allelic difference), two of which contained isolates from the United Kingdom. Clofazimine and guideline-recommended antimycobacterial agents showed good in vitro efficacy, except rifampicin, with 23.6% resistance. This study represents a major expansion of M. xenopi genomic resources and provides insights into the genomic population structure, phenotypic susceptibility, and clinical characteristics of M. xenopi. Guideline-recommended antimycobacterials show good in vitro activity, while clofazimine may be a valuable addition to M. xenopi therapy. The identified clusters underscore the need for further investigation into transmission dynamics and globally successful clones.IMPORTANCEMycobacterium xenopi is an increasingly recognized opportunistic lung pathogen that is difficult to treat. Infections often occur in patients with pre-existing health conditions and can present substantial diagnostic and therapeutic challenges. A deeper understanding of its genetic diversity and resistance mechanisms is essential for optimal patient management and for clarifying potential transmission routes. By analyzing 76 whole-genome sequences together with detailed clinical information and phenotypic drug-susceptibility data, this study substantially expands the available genomic repertoire for M. xenopi. While clinical relevance was limited in our cohort, most guideline-recommended antimicrobial agents showed good efficacy in vitro. The detection of closely related strains might point toward a common environmental source of infection. These findings highlight the need for continued surveillance and provide a comprehensive foundation that supports more accurate monitoring, improved understanding of disease behavior, and future investigations into M. xenopi pathogenicity.

Humans↗

PubMed2025

SPC: a SPectral Component approach leveraging Identity-by-Descent graphs to address recent population structure in genomic analysis.

Population structure is a well-known confounder in statistical genetics, particularly in genome-wide association studies (GWAS), where it can lead to inflated test statistics and spurious associations. Traditional methods, such as principal components (PCs), commonly used to adjust for population structure, are limited in capturing fine-scale, non-linear patterns that arise from recent demographic events - patterns that are crucial for understanding rare variant effects. To address this challenge, we propose a novel method called SPectral Components (SPCs), which leverages identity-by-descent (IBD) graphs to capture and transform local, non-linear fine-scale population structure into continuous representations that can be seamlessly integrated into genetic analysis pipelines. Using both simulated datasets and empirical data from the UK Biobank (N ≈ 420,000), we demonstrate that SPCs outperform PCs in adjusting for fine-scale population structure. In simulations, SPCs explained over 90% of the fine-scale population structure with fewer components, while PCs captured less than 5%. In the UK Biobank, SPCs reduced the inflation of p-values in the GWAS of an environmental-driven phenotype by 12% compared to PCs, while maintaining a similar performance to PCs in height, a highly heritable phenotype. Additionally, SPCs improved rare variant association analyses, reducing genomic inflation (e.g., from 7.6 to 1.2 in one analysis), and provided more accurate heritability estimates. Spatial autocorrelation analysis further confirmed the ability of SPCs to account for environmental effects, reducing Moran's I for both environmental and heritable phenotypes more effectively than PCs. Overall, our findings demonstrate that SPCs provide a robust, scalable adjustment for recent population structure, offering a powerful alternative or complement to PCs in large-scale biobank studies.

GWAS↗

PubMed2025

Global genomic population structure of wild and cultivated oat reveals signatures of chromosome rearrangements.

The genus Avena consists of approximately 30 wild and cultivated oat species. Cultivated oat is an important food crop, yet the broader genetic diversity within the Avena gene pool remains underexplored and underexploited. Here, we characterize over 9000 wild and cultivated hexaploid oat accessions of global origin using genotyping-by-sequencing and explore population structure using multidimensional scaling and population-based clustering methods. We also conduct analyses to reveal chromosome regions associated with local adaptation, sometimes resulting from large-scale chromosome rearrangements. We report four distinct genetic populations within the wild species A. sterilis, a distinct population of cultivated A. byzantina, and multiple populations within cultivated A. sativa. Some chromosome regions associated with local adaptation are also associated with confirmed structural rearrangements on chromosomes 1A, 1C, 3C, 4C, and 7D. This work provides evidence suggesting multiple polyploid origins, multiple domestications, and/or reproductive barriers amongst Avena populations caused by differential chromosome structure.

Avena↗

PubMed2026

Reference-Guided Chromosome-Scale Genome Assembly With Insights on Population Genomics of the Atlantic Goliath Grouper (Epinephelus itajara), Islas del Rosario, Colombia.

Epinephelus itajara, commonly known as the Atlantic Goliath grouper, is the largest species among the western North Atlantic groupers and is critically endangered. This species plays a crucial ecological, cultural, and economic role and has been the focus of captive breeding efforts at the Oceanario of the Rosario Islands, Colombia. However, despite its ecological and conservation importance, genomic resources and population genomic data for E. itajara remain scarce, particularly in the Colombian Caribbean. This study presents a reference-guided chromosome-scale genome assembly and an analysis of the population genomic structure of E. itajara using PacBio HiFi sequencing and Illumina technologies. The assembled genome has a total size of 1.12 Gb, with a contig N50 of 42.69 Mb and a scaffold N50 of 46.30 Mb. A total of 22,692 protein-coding genes were identified after masking 46% of the genome, which consists of repetitive elements. Comparative genomic analyses revealed a high degree of collinearity with closely related Epinephelus species and identified E. lanceolatus as the closest relative, supporting recent divergence and conserved genome architecture within the genus. Additionally, a population genomics analysis was conducted using 7706 high-quality SNPs to assess the genomic structure of captive populations. The results revealed four distinct genomic lineages, with moderate genetic differentiation among the sampled individuals. In the Colombian Caribbean, two unique lineages were identified, associated with the localities of Bahía Cispatá and Bahía Barbacoas, suggesting possible geographic isolation. These genomic resources provide valuable tools and new opportunities to better understand the genomic diversity, evolutionary history, and reproductive mechanisms of E. itajara. Moreover, they serve as a foundation for conservation strategies, including selective breeding programs aimed at increasing genomic diversity in captive populations and guiding restoration efforts in its natural habitat.

Epinephelus itajara↗

PubMed2026

Comparative genomics reveals population structure and functional differentiation in Limosilactobacillus fermentum.

Limosilactobacillus fermentum is a widely distributed lactic acid bacterium frequently detected in fermented foods and host-associated microbiota, yet its global genomic diversity and functional variability remain insufficiently characterized. Here, we performed a large-scale comparative genomic analysis of 336 high-quality L. fermentum genomes curated from public databases. Species identity was validated using average nucleotide identity (ANI), and population structure was examined using pairwise ANI comparisons together with Mash-based phylogenetic reconstruction. Clustering at ≥ 99% ANI resolved the dataset into 15 genomic clusters, with four dominant lineages comprising the majority of genomes. Pangenome reconstruction identified 5,853 gene clusters, including 1,325 core genes (22.6%) and a large accessory component dominated by low-frequency genes. Heap's law modeling (λ = 0.19) indicated a weakly open pangenome, suggesting ongoing gene acquisition as additional genomes are sampled. Functional annotation revealed that core genes were primarily associated with essential cellular processes, whereas accessory genes were enriched in carbohydrate metabolism, membrane-associated functions, and defense-related systems. Variation in carbohydrate-active enzymes (CAZymes), transport systems, and stress-response genes was observed across lineages, indicating strain-level functional diversity. Although genomes from human and food sources were broadly distributed across phylogenetic lineages, multivariate analysis showed that gene-content variation was more strongly associated with genomic lineage than with isolation source. These results provide a population genomic framework for understanding genomic diversity and functional potential in L. fermentum.

Phylogeny↗

PubMed2026

Emerging trends in invasive Streptococcus dysgalactiae subsp. equisimilis infections in Denmark, 2014 to 2024: a nationwide genomic and registry-based study.

BACKGROUNDIncreasing incidence rates of invasive Streptococcus dysgalactiae subspecies equisimilis (iSDSE) have been detected worldwide.AIMWe aimed to investigate iSDSE infection incidence rates in Denmark during 2014-2024, and characterise the genomic population structure of a subset of iSDSE isolates and their antimicrobial resistance (AMR).METHODSUsing national register data, we estimated overall and sex-/age-stratified iSDSE incidences during 2014-2024, by retrospectively identifying cases of invasive infections with group C and G streptococci or S. dysgalactiae (including specified as subspecies equisimilis). From the voluntary national beta-haemolytic streptococci laboratory surveillance system, whole-genome-sequenced isolates from August 2020-September 2022 were used to investigate the iSDSE genomic population structure. Susceptibility to penicillin, erythromycin and clindamycin was determined and AMR genes identified.RESULTSDuring 2014-2024, iSDSE incidence rates increased significantly (linear trend analysis p < 0.001) with mean annual incidence ranging between 10.3 and 16.4 per 100,000, peaking in 2023. Incidence was higher in males, increasing with older age. Nearly 75% of the 1,223 iSDSE isolates belonged to four of 14 genetic clusters. Sequence types (STs) ST20 and ST17 were most prevalent, while emm-type stG62647, a variant associated internationally with higher virulence, dominated. All isolates were phenotypically susceptible to penicillin but approximately 10% were respectively erythromycin and clindamycin resistant. High erythromycin resistance prevalence (57%; 39/68), coinciding with gene ermA, occurred in one genetic cluster.CONCLUSIONThe findings illustrate the need for national registry-based surveillance to detect epidemiological changes and potential outbreaks. Further, continuous genomic surveillance can monitor the occurrence and expansion of genetic clades and AMR genes.

Denmark↗

PubMed2026

Whole-Genome Sequencing Reveals Population Structure, Genetic Diversity, and Selection Signatures in Kazakh Dromedary and Bactrian Camels.

Understanding the genomic basis of environmental adaptation is essential for the conservation and genetic improvement of domestic camels. In this study, we investigated the population structure, genetic diversity, and genomic variation potentially associated with environmental adaptation of Kazakh dromedary and Bactrian camels using whole-genome sequencing. Whole-genome sequencing data were generated for Kazakh camels (15 dromedaries and 16 Bactrian camels) and integrated with 131 publicly available genomes representing camel populations from the Arabian Peninsula, Iran, Xinjiang, Inner Mongolia, and Mongolian wild camels. Population structure, genetic diversity, and genome-wide selection were evaluated using principal component analysis, ADMIXTURE, nucleotide diversity, linkage disequilibrium, runs of homozygosity, genomic inbreeding (FROH), and selection scans based on FST, θπ ratio, and XP-EHH. Population genomic analyses revealed clear differentiation between dromedary and Bactrian camels, whereas Kazakh camel populations exhibited higher nucleotide diversity (θπ = 1.307-1.551 × 10-3), and lower genomic inbreeding (median FROH: 0.037-0.056) than Arabian populations. Genome-wide selection analyses identified MC4R as the prominent candidate gene in Kazakh dromedaries and RYR1 as a prominent candidate gene in Kazakh Bactrian camels. Functional enrichment analyses highlighted pathways related to energy metabolism, thermogenesis, calcium signaling, skeletal muscle function, mitochondrial activity, and oxidative stress response. These findings provide new insights into genomic variation potentially associated with environmental adaptation in Kazakh camels and offer valuable genomic resources for future conservation, breeding, and evolutionary studies.

MC4R↗

PubMed2025

Temporal Genomics Reveal a Century of Genomic Diversity Shifts Across a Biodiversity Hotspot Avian Assemblage.

Biodiversity has experienced tremendous shifts in community, species, and genetic diversity during the Anthropocene. Understanding temporal diversity shifts is especially critical in biodiversity hotspots, i.e., regions that are exceptionally biodiverse and threatened. Here, we use museomics and temporal genomics approaches to quantify temporal shifts in genomic diversity in an assemblage of eight generalist highland bird species from the Ethiopian Highlands (part of the Eastern Afromontane Biodiversity Hotspot). With genomic data from contemporary and historical samples, we demonstrate an assemblage-wide trend of increased genomic diversity through time, potentially due to improved habitat connectivity within highland regions. Genomic diversity shifts in these generalist species contrast with general trends of genomic diversity declines in specialist or imperiled species. In addition to genetic diversity shifts, we found an assemblage-wide trend of decreased realized mutational load, indicative of overall trends for potentially deleterious variation to be masked or selectively purged. Across this avian assemblage, we also show that shifts in population genomic structure are idiosyncratic, with species-specific trends. These results are in contrast with other charismatic and imperiled African taxa that have largely shown strong increases in population genetic structure over the recent past. This study highlights that not all taxa respond the same to environmental change, and generalists, in some cases, may even respond positively. Future comparative conservation genomics assessments on species groups or assemblages with varied natural history characteristics would help us better understand how diverse taxa respond to anthropogenic landscape changes.

Animals↗

PubMed2026

Genome-wide SNP-based genomic diversity and population structure analysis in alpaca populations from Europe and Peru.

This study aimed to analyze the genetic diversity and population structure of alpacas in Germany, Switzerland, and Austria (German-speaking regions, GSR) and to compare with that of the country of origin of the species (Peru). A total of 179 animals from GSR and 151 from Peru were genotyped with a species-specific 76k SNP array. The observed and expected heterozygosity was 0.305 and 0.311 for GSR and 0.310 and 0.312 for Peru. The mean FROH values were 0.029 for GSR and 0.023 for Peru. In general, results show that breeders in both analyzed regions efficiently maintain genetic diversity. Principal component analysis identified the GSR and Peru populations as separate from each other, but the relative proximity of both clusters indicates the shared genetic heritage. FST and XPEHH methods identified genomic regions under selection for traits such as coat color and adaptation. Genome-wide association studies comparing black and brown with white or gray alpacas identified associated genome regions containing the ASIP and KIT genes, respectively. The association of a recently identified keratin locus on chromosome 16 with differences in fleece type in alpacas was confirmed, while the putative causality of a TRPV3 variant was rejected.

Animals↗

PubMed2026

Comparative genomic analysis reveals distinct population structure in Legionella anisa.

Legionella anisa has been frequently isolated from engineered water systems; however, its population structure remains understudied compared to Legionella pneumophila. Here, we generated complete genome sequences for four L. anisa isolates recovered from a healthcare facility in Rimouski, Canada. Further the population structure of this species was investigated by performing comparative genomic analyses of the genomes generated in this study together with publicly available L. anisa genomes. Genome-wide phylogenetic analysis revealed the presence of three distinct clades separated by substantial genetic divergence (∼500 SNP), with the Rimouski isolates forming a tightly clustered group, suggesting a clonal lineage. Comparative pangenome analysis indicated moderate core genome conservation accompanied by a highly variable accessory genome (∼50%). The isolates characterized in this study harbored multiple plasmids encoding genes associated with conjugation, heavy metal resistance, and other stress-related functions, suggesting potential roles in environmental persistence. Previous studies have shown that L. anisa can proliferate within protozoan host cells, although outcomes vary depending on the host species. Our isolates showed efficient proliferation within Acanthamoeba castellanii, but not within Vermamoeba vermiformis, under the conditions tested. Together, these findings underscore the genomic diversity of this understudied Legionella species and provide a framework for future investigations regarding environmental persistence and potential pathogenicity.

Legionella anisa, Whole genome sequencing↗

PubMed2026

A genome-wide assessment of the population structure of thirteen admixed and pure Australian beef cattle breeds.

Knowledge of population structure is a key factor for successful multi-breed genomic prediction, especially in single-step analysis when metafounders are considered. In Australia, current assessments mostly focus on single breeds using a single-step genomic prediction method. However, the effective integration of pedigree, phenotypic, and genomic data in a multi-breed framework still requires further research, especially for combined analyses including admixed and multi-breed populations. This study began with 602,952 genotyped individuals with 8K SNPs in common from 13 beef cattle breeds (Alexandria, Angus, Brahman, Brangus, Charolais, Droughtmaster, Hereford, Kynuna, Limousin, Santa Gertrudis, Shorthorn, Speckle Park, and Wagyu). Due to different numbers of animals being genotyped in each breed, a representative subset of animals was chosen by employing a validated sampling strategy using Gaussian Mixture Models (GMM) complemented by Principal Component Analysis (PCA) within each breed. Subsequently, a specific number of animals in each cluster were randomly selected to capture the entire genetic diversity per breed, with a total of 260 animals from each breed. The first three principal components explained 59.89% of the total variation, with PC1 (33.54%) clearly separating Bos indicus from Bos taurus lineages. Admixture analysis identified stable ancestral components and defined the genetic makeup of both pure and composite populations. The results showed extensive genetic diversity in some breeds and highlighted distinct genetic differences between Bos indicus and Bos taurus breeds. In addition, six composite breeds' admixture levels confirmed their origin and breed history, revealing a directional shift in ancestry proportions by a longitudinal increase in Brahman ancestry within tropical composites over time. Thus, the findings pave the way for more effective utilization of genetic diversity both within and across populations and provide a framework for designing multi-breed genetic evaluations and breeding programs to improve productivity and profitability in Australian beef production.

Animals↗

PubMed2026

Low-pass whole-genome sequencing reveals genomic diversity and ecotype-specific adaptation in indigenous Tigrayan chickens.

Indigenous chickens play a critical role in food security and climate resilience in smallholder systems, yet their genomic diversity and adaptive potential remain insufficiently characterised. This study employed low-pass whole-genome sequencing (LP-WGS; 0.2-1.99×) to investigate genomic diversity, population structure, inbreeding and candidate environment-associated genomic variation in 33 chickens from highland, midland, and lowland agroecologies in the Tigray region of northern Ethiopia. After imputation and stringent filtering, 23.4 million high-confidence SNPs were retained, including ~ 17% novel variants, indicating substantial uncharacterised genetic diversity in these populations. SNP density (13.8 ± 8.6 SNPs/kb) was comparable to values reported from high-coverage Ethiopian chicken datasets, demonstrating the suitability of LP-WGS for population genomics in resource-limited settings. Marked differences in genomic diversity were observed among ecotypes: midland chickens showed the highest nucleotide diversity (π = 0.00267), followed by lowland (π = 0.00233), whereas highland chickens showed the lowest diversity (π = 0.00203) and elevated genomic inbreeding (FROH and FHOM ≈ 0.18). Population structure analyses revealed clear genetic separation among ecotypes. PCA (13.91% variation explained) distinguished lowland chickens along PC1 and separated highland from midland along PC2, while ADMIXTURE and FST patterns supported three major ancestral genomic backgrounds. Functional annotation of private missense variants uncovered distinct adaptive signatures reflecting the contrasting agroecological conditions. Highland chickens showed enrichment of candidate genes potentially involved in physiological processes relevant to high-altitude environments, including cold response, angiogenesis, cardiovascular regulation and metabolic homeostasis (eg., PARP1, ACOX2, ITGB3, EDNRB, SOX8, and SOX10). Midland chickens exhibited candidate signals of selection in genes with known roles in innate antiviral immunity, bacterial defence and inflammatory regulation (eg., BAK1, CLSTN1, CYSLTR1, CYSLTR2, CXCR7, GIPR, DSCAM, GDAP1, TLR3, TLR4, TLR7, IFIH1, ADORA1, EPHB1, and TMPRSS2). Lowland chickens displayed candidate variants associated with heat-stress response, DNA damage repair, oxidative balance and cardiovascular support under extreme temperatures (e.g., MLH1, BDKRB1, GPR19, FLT1, CCL18, TGM2, and RAMP3). Overall, the results indicate substantial genomic differentiation among ecotypes and suggest candidate environment-associated genetic divergence across Tigray's diverse agroecological zones. These populations may represent important reservoirs of adaptive genetic variation for climate-resilient poultry breeding, warranting further functional validation and conservation-oriented management.

Animals↗

PubMed2025

Largest-Scale Genomic Resource Reconstructing the Genetic Origin, Population Structure, and Biological Adaptations of the Hui People.

Historical and archaeological records indicate that the Maritime and Land Silk Roads played a pivotal role in facilitating Trans-Eurasian migrations and cultural exchanges. However, the extent to which population movements or the spread of ideas shape Chinese Hui populations remains debated. We present the largest genomic resource to date, including 2,280 Hui individuals sequenced or genotyped from 30 diverse regions, to examine the genetic origins, population structure, and biological adaptations of this underrepresented group in global human genome research. We identified a detailed population structure characterized by five distinct genetic lineages of the Hui, influenced by geography and varying gene flow. The admixture history and demographic events suggest that the northwestern and northern Hui lineages emerged from demic diffusion during the Tang and Yuan Dynasties via the Land Silk Road. In contrast, the southern and island Hui lineages reflect cultural diffusion along the Maritime Silk Road, while the mixed southern-northern lineage likely developed through a combination of demic and cultural diffusion. Our findings support a hybrid model for Hui formation, indicating that both demographic processes and sociocultural transmissions contributed to their population history. We identified east-west highly differentiated variants and pre- and post-admixture adaptations in Hui genomes, demonstrating that admixture-driven adaptive or neutral variants impacted susceptibility to cardiovascular diseases and immune- and diet-related traits. These adaptive signatures include post-admixture signals of SLC24A5 and ECHDC1 in the Hui, as well as pre-admixture signals of the HLA region, BCL2A1, and KCNH8 in the East Asian source. Overall, our study suggests that Han-related genetic components helped the Hui population rapidly adapt to new local environments. Additionally, the frequency spectrum of clinically essential variants differed significantly between Hui and Han individuals, emphasizing the importance of including underrepresented populations in genomic research to promote health equity.

Humans↗

PubMed2026

Genomic analysis of breed composition and population structure in Montana composite cattle.

The Montana composite was developed in Brazil from crosses between Bos indicus and Bos taurus and structured into four biological types: Zebu (N), adapted taurine (A), British taurine (B), and continental taurine (C). This study aimed to characterize the genetic diversity and population structure of the Montana composite using genomic data through principal component analysis (PCA), admixture analysis, and Wright's FST statistic. The PCA revealed a clear separation between Bos indicus and Bos taurus groups, with Montana animals distributed in an intermediate position. The first two principal components explained 69.48% and 3.45% of the total variation, respectively. Supervised admixture estimates indicated a predominance of taurine contribution, with type A accounting for 34.47%, 52.64%, and 51.71% at K = 4, 9, and 11, respectively. Increasing the ancestry resolution refined the contribution of individual founder breeds without changing the overall predominance of taurine ancestry. Comparisons between breed proportions obtained from pedigree and genomic data revealed significant differences, for most biological types and ancestry models (P < 0.001), indicating that realized breed composition deviates from theoretical expectations. Estimates of genetic differentiation confirmed greater divergence between Zebu and taurine groups, as well as reduced distances among populations sharing common ancestry. Specific relationships were identified between the composite and some of its founder breeds, particularly Belmont Red, Senepol, and Tuli. Overall, the results demonstrate that the Montana composite has a complex genomic structure, with genomic ancestry varying according to the resolution adopted and differing from pedigree-based expectations.

Animals↗

PubMed2026

Genome-Wide SNP Characterisation of Three Kazakh Sheep Breeds: Kazakh Fat-Tailed Coarse-Wool, Degeres, and Etti Merino.

Kazakhstan's sheep portfolio underpins much of the country's mutton and wool production, yet several of its principal breeds remain genomically uncharacterised. The aim of this study was to characterise the genomic diversity, population structure, and global phylogenetic placement of three economically important Kazakh breeds and to determine whether they constitute separate gene pools requiring independent management. We present the first genome-wide SNP characterisation to include the Degeres (DE), the Etti Merino (EM), and the Kazakh fat-tailed coarse-wool (KKG) breeds simultaneously. A total of 1497 animals (DE = 354, EM = 642, KKG = 501) sampled across seven production households were genotyped and, after quality control, analysed at 42,279 SNPs, of which 22,766 LD-pruned markers were used for principal component analysis and AMOVA. We applied principal component analysis (PCA), pairwise FST, analysis of molecular variance (AMOVA), neighbour-joining phylogenetics, model-based ancestry estimation (ADMIXTURE), and Hill-number diversity profiling, and projected the breeds against the global Ovine SNP50 HapMap panel (74 reference breeds, 2819 animals; 37,685 shared SNPs). All three breeds retained uniformly high within-breed diversity (expected heterozygosity 0.413-0.417) with fixation indices at or near zero. AMOVA partitioned 94.03% of variance within breeds (ΦST = 0.060, p < 0.001). PCA, phylogeny, and ADMIXTURE concordantly resolved three breed-specific clusters at K = 3, with a maximum interbreed FST of 0.038 within the study dataset. Against the global panel, EM was genetically closest to Merino and Merino-derived reference breeds (pooled FST = 0.017) and substantially more distant from Southwest Asian sheep (FST = 0.045), whereas DE and KKG showed the reciprocal pattern (FST = 0.027 and 0.020 to Southwest Asia, 0.052 to the Merino group). DE additionally displayed the heterozygote excess and partial admixture expected of an incompletely consolidated composite. These results delineate three distinct gene pools and carry direct implications for breed management and the conservation of genomic diversity in Kazakhstani sheep.

ADMIXTURE↗

PubMed2026

Larval Genomics as a Viable, Fisheries-Independent Tool for Investigating Population Structure in Tropical Pacific Tunas.

Understanding how dispersal, life history, and environmental variability shape genetic connectivity in the open ocean remains a central challenge in evolutionary biology. Highly migratory marine predators like tunas have traditionally been considered genetically homogeneous across ocean basins, yet emerging genomic evidence suggests that cryptic population structure can persist even in species with high gene flow and large effective population sizes. We used 2bRAD sequencing of 348 larval and subadult skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), and bigeye tuna (T. obesus) collected from the central Pacific across 7 years of sampling to examine species boundaries, population genetic information, genetic structure, and connectivity. Larval sampling revealed consistent spawning by all three species and enabled unbiased detection of genetic patterns prior to recruitment bottlenecks. We found strong divergence amongst species, no evidence of structuring within skipjack or bigeye, and a divergent yellowfin population detected in 2 consecutive sampling years north of American Samoa. Comparisons between larvae and subadults suggest that sampling early life history stages can be a valuable tool for assessing population genetic information before recruitment bottlenecks, selective harvest by fisheries, adult dispersal, and selective pressures acting on adult populations, thereby contributing novel insights to the research and effective management of these species. These results highlight how larval genomics can complement traditional population genomic studies of adult tunas and reveal fine-scale structure in highly vagile species, providing new perspectives on connectivity in the open ocean.

Animals↗

PubMed2025

Differential Alloreactivity: Lessons Learned From a Singular HLA Locus.

Alloreactivity entails the recognition of cells and tissues from one individual as foreign by T cells and other immune effectors from another individual. Alloreactive immune responses play an important role in various clinical contexts, in particular in transplantation. Major drivers of these responses are the highly immunogenic, non-self HLA molecules. However, the immunogenicity of these allogeneic HLA molecules has been observed to vary according to certain immunobiological and immunogenetic parameters, leading to the concept of differential alloreactivity. Recent progress in unveiling the underpinnings of this phenomenon has been made for the frequently mismatched HLA-DP allotypes, whose singular genomic, structural and population genetics characteristics offer an ideal scenario for these investigations. Studies in the HLA-DP context have highlighted the immunopeptidome overlap between self and non-self HLA allotypes, as well as its editing by non-classical class II chaperones HLA-DM and HLA-DO, as a main determinant of their immunogenicity likely via indirect effects of thymic education. Recent evidence suggests that these observations could also be extended to alloresponses directed against HLA molecules encoded by other loci. How these functional characteristics of HLA molecules shape allorecognition by T-cell subsets, and how they translate into different clinical consequences in the context of transplantation will be the subject of the present review.

Humans↗

PubMed2026

Chromosome-Scale Genome of Zoonotic Eyeworm Thelazia callipaeda from China.

Thelazia callipaeda is a vector-borne zoonotic eyeworm infecting companion animals, wildlife, and humans, but chromosome-scale genomic resources from Chinese clinical material remain limited. We generated a genome supported by Pacific Biosciences (PacBio) high-fidelity (HiFi) sequencing and high-throughput chromosome conformation capture (Hi-C) from 100 adult worms recovered from naturally infected dogs in Beijing and compared its chromosome-scale organization with Portuguese assembly GCA_965194785.1. The final assembly spans 119.53 megabases (Mb) and comprises 115 top-level sequences, including four pseudomolecules totaling 91.26 Mb (76.34%) and 111 unanchored sequences. Genome-mode Benchmarking Universal Single-Copy Orthologs (BUSCO) analysis recovered 98.5% complete chromadorean orthologues, and the representative 11,788-protein gene set recovered 92.6%. Sequence-level alignment resolved Chinese chromosomes 1-4 (chr1-chr4) to Portuguese chr1, chrX, chr3, and chr2, respectively, with retained alignments covering 95.9-99.2% of each Chinese pseudomolecule and estimated sequence identities of 99.75-99.91%. Strong chromosome-scale collinearity was accompanied by localized reverse-collinear regions, including 0.243 Mb and 0.115 Mb intervals on chr2-chrX and chr3-chr3. The anchored sequences contained 96.7% of predicted genes and were substantially more gene-dense than the unanchored sequences. These results establish a clinically sourced Chinese chromosome-scale reference and provide a validated framework for future individual-worm, population-genomic, structural-variation, and comparative genomic studies of this parasite.

Hi-C↗